Watercolor printing



Dec, 29,1931. H. N. DURHAM 1,338,218

WATERCOLOR PRINTING Filed Dec. 26, 1928 WATER RECEPHVE SURFACE RELIEF PR\NTING/ Dl,ATE

WATER-REPELLANT WATER'-F2E(ZEPTI\IF. URFAC E U FACE RELIEF PRINTING WATER RECEPTIVE COLLOID 4 1 r1 W1 A y 1 i ump MET/1L FLHTE Patented Dec. 29, rest TFL'QBART No DURHAM, OF JTAGKSIDN EMGEEEL YQRK WATEEGQLQR PRETTIISG} Application filed December 36, 1928. Serial 1%. 328.6%.

This inventionrelates to water color printing and more especially to new and useful improvements in the plates therefor, to a process for producing such plates and toa P process of printing with said plates.

Among the objects of the invention are the simple expeditious and economical production of durable plates for printing with wator-color inks and the provision of a process whereby plates for printing with water color inlrs may be satisfactorily employed for the production of a large number of high grade impressions. These and other objects-of the invention will in part be obvious and in part will be set forth hereafter.

The invention consists in the novel steps, processes, combinations and improvements herein shown and described,

The accompanying drawings illustrate two typical embodiments of the present invention and:

Figure 1 is a greatly enlarged cross-section of a printing plate in accordance with the present invention, and for use in connection with the process of the present invention, and

Figure 2 is a greatly enlarged cross-section of a modified form of printing plate for use in connection with the invention...

Fig. 3 is a diagrammatic and enlarged cross section of a further modification of the invention in which the ink receptive portions have been treated with a water-receptive colloid, such as gum arabic.

Briefly, mg process consists in the following steps: relief printing plate of metal, which may be either a line or a half-tone printing plate produced by photoengraving, stereotyplng, electrotyping or by any other suitable process, is treated to. minutelycavino tate the surface. as by etching, sandblasting,

abrading or electrolytically to render the relief portions of the printing plate water-. receptive so they will retain a thin, even film of aqueous liquid, such as an aqueous solution of dye. After this treatment, the plate may be coated, if desired, with a thin solution of gum arabic and dried, but in most cases, and generally where the plate is to be used within a short space of time this operso ation can be dispensed with. -As soon as the treatment of the plate to render it water. receptive has been completed, the plate may be placed on the press and printed in the usual manner, using, in place of the customary oleaginousink, an aqueous solution of dye,

to which may be added, if desired, a small amount of glycerin and gum arabic, with or without the addition of a compound adapted to maintain the relief or ink-receiving portlon of the plate in a water-receptive condi Q9 tion. If desired, other vehicles than water can be employed so long as they are readily volatile.

In certain types of work, it will be found highly advantageous and desirable to fill at 5 least a portion of the depressions, orintaglio portions, lying between adjacent relief portions of the printing surface and preferably the smaller of such depressions, with an oleaginous or unctuous material which is preferm ably thermoplastic, to cause these portions to be strongly water-repellent, but leaving the nelief pbrtions of the plate water-receptive.

In the preferred form for carrying out my invention, and considering the same as applied to the production of water-color prints by the use of rinting plates made of zinc, the original p ate may be produced by any suitable or desired process capable of giving a relief printing plate. Assuming that a so line photoengraved plate is employed for this purpose, the enamel remaining on the printing surface is thoroughly removed and, if desired, the depressions in the face of the plate are filled with an olea inous or unctuous substance such as para n or tallow, by pouring the molten substance over the plate in sufficient quantity to cover the plate, after which the substance is allowed" to harden. When sufficiently hardened, the water-re- 90, pellent, oleaginous or unctuous substance is scraped off the surface of the plate until it is level with or slightly lower than the relief portions of the met-a1 forming the pointmg surface of the plate, and the relief port-ions are thoroughly cleaned of any adherent oleaginous or unctuous substance. After th1s has been completed, or after the enamel has been removed in case the ink rejecting layer is omitted, the plate is treated to render the relief portions, which areto be inked, minutely cavltated and therefore, water-receptive. This may be accomplished in any one of several manners, but is preferably carried out by etching the plate for several minutes with a composition adapted to render those portions water-receptive and thereby enable them to retain a thin, even film of aqueous liquid, such as a water color ink hereinafter referred to'more in detail.

Preferably this etching composition is a dilute solution of phosphoric acid (2-3% H PO but its composition may be widely varied and many other compositions, such. as a dilute, slightly acidified solution of potassium or ammonium bichromate will be found suitable. When the plate has been sufiiciently etched in the manner described, it should be thoroughly washedwith water to free it from the etching solution.

In case the plate is not to be used for a.

considerable length of time, it will be found desirable to flow it with a dilute solution of gum arabic, after which the plate is dried, thereby preventing substantial oxidation of the water-receptive surface and increasing the water receptive qualities of the relief portions of the plate.

The plate is now ready to be placed on the press and this is done in the usual manner and need not be described in detail, or the plate may, if desired, be printed by hand, and producing a plate as shown in Fig. 3.

In printing the plate, there is preferably employed an aqueous solution of dye, which may contain a small proportion of glycerin.

and gum arabic in addition to its other constituents. If a large number of impressions are to be taken from the plate, and where the nature of the coloring matter employed in the ink will permit it, it will often be found desirable to add a small amount of the etching agent to the ink so as to maintain the printing surface in a water-receptive condition thereby insuring a continued even distribution and retention of the aqueous ink'.

Referring now to the accompanying drawings illustrating two forms of printing plates suitable for use in connection with the process of the present invention, and forming part of the present invention:

Figure 1 shows a relief printing plate, preferably formed 0 metal, such as zinc, in which the relief portions of the plate are the inkrecepti've portions of the plate and have been treated in the'manner indicated above to render them water-receptive and capable of retaining a film of water-color ink, the portions not to be inked being etched or otherwise depressed below thegeneral surface of the plate.

Figure 2 illustrates alternative embodiment of .a printing plate for water color printing; and as shown in this figure the plate may be a relief printing plate formed of metal such as zinc, the relief portions of the plate being treated to render them Water-receptive, as set forthabove, and the depressed portions of the plate being filled level with the surface of the plate, or slightly below the surface of the plate, with. a water-repellent material of the nature de scribed above.

As will be readily apparent, many changes in the above preferred process can be made without departing from the basic principles underlying my invention, and,'by way of example, the printing surface of the plates may be rendered water receptive by abrasion,- or by electrodeposition thereon of a thin film of metal, copper or other plates may be employed in place of the zinc plates and other etching materials may be employed than- 8 those mentioned.

The term etch 'as used in the specification includes not only treatment with a corrosive acid, but also the equivalent processes of rendering the metal surface minutely cavitated andwater-receptive, such as abrading, etc.

What I claimis: v

1. A metal printing plate having relief portions to be inked with water color ink, said relief portions being rendered waterreceptive and a water-repellent material substantially filling at least a portion of the areas between the relief portions.

2. Theprocess of preparing relief metal printing plates for printing with water color inks which comprises substantially filling at least a portion of the depressions lying between the relief portions of the plate with a water-rejecting substance and then rendering the relief portions of the plate capable of retaining an even film of water-color ink.

3. The process of preparing relief metal plates for printing with aqueous inks which includes, filling at least a portion of the intaglio portions of the plate with an oleaginous or unctuous composition and treating the relief portions of the plate to render them capable of retaining a thin even film of aqueous ink. v

4. The process of preparing relief, metal printing plates for printing which includes rendering the relief portions capable of retaining a thin even film of an ink having a volatile vehicle and treating the depressed portions of the plate so they will reject such an ink.

' 5. The process of preparing relief metal plates for printing with aqueous inks which includes, filling at least a portion of the intaglio portions of the plate with an oleagi- I \face with a thin film of gum to prevent oxidation.

6. The process of preparing plates for water color printing including etching the relief portions of a relief printing plate to render them water receptive.

7 The process of preparing plates for water color printing including minutely cavitating the surface of the relief portions of a printing plate to render them water receptive.

8. The process of preparing plates for water color printing including removing the enamel from an etched photoengraved plate and coating the relief portions -of the plate with a solution of a water soluble colloid and drying the coating to render the relief surfaces of the plate highly water receptive.

9. The process of preparing plates for water color printing including removing the enamel from an etched photoengraved plate, etching the relief portions of the plate and coating the relief portions of the plate with a solution of a water soluble colloid and drying the coating to render the relief surfaces of the plate highly water receptive.

10. The process of Water color printing which includes etching a photoengraved relief plate to render its surface water-receptive and inking the plate withan aqueous solution of a dye.

- 11. The process of water color printing which includes minutely cavitating the relief portions of a photoengravedplate to render it water-receptive and inking the relief portions with an aqueous solution of dye.

12. The process of preparing metal plates for water color printing including cleaning the relief ortion of the plate and coating the relief portion of the plate with a coating of a water soluble colloid to render the relief surfaces of the plate highly water receptive.

In testimony wherof, I have signed my name to this specification.

HOBART N. DURHAM. 

